Single-channel properties of α2 GlyRs in the cell-attached configuration. (A) Traces on the left are continuous stretches (20 s) of single-channel currents from α2 GlyRs expressed in HEK293 cells (pipette holding V, +100 mV) recorded in the presence of 20 µM to 10 mM glycine (5–7-kHz filter). On the right are the corresponding open-period and shut-time distributions, fitted with mixtures of exponential probability density functions. (B) α2 GlyR single-channel currents in 20 µM and 10 mM glycine are compared with equivalent traces recorded from HEK293 cells expressing α1β GlyRs, under similar recording conditions (from Burzomato et al., 2004). Note the long bursts for α2 channels at the low glycine concentrations. (C) The Popen concentration–response curve for α2 receptor clusters at a range of glycine concentrations is shown. Each point in the plot represents the average Popen value for all idealized patches at each concentration. The Popen for each patch was calculated as the ratio between the total open time and the total length of the clusters.
